A new study from two of NASA's "Great Observatories" provides fresh insight into how some stars are born, along with a beautiful new image of a stellar nursery in our own Milky Way Galaxy. While astronomers have long understood that stars and planets form from the collapse of a cloud of gas, the main causes of this process have remained mysterious. Now, research on an object known as Cepheus B, a cloud of hydrogen about 2400 light years from Earth, helps answer that question. X-rays seen by Chandra show where the young stars in the cloud are, while infrared emission observed by Spitzer reveals whether these stars contain planet-forming disks around them. Taken together, these data reveal that radiation from massive stars is triggering a new generation of stars to be born. This happens more often than previously thought.
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Astronomers observed an object known as Cepheus B, which is a cloud of molecular hydrogen about 2,400 light years from Earth. X-ray data from Chandra allowed the researchers to pick out the young stars within around Cepheus B. Infrared emission detected by Spitzer revealed whether the young stars had disks around them in which stars may form. By combining the two sets of data, astronomers found that stars in this object are being triggered to form by some external force, such as radiation from a massive star or a shock from a nearby supernova.
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This composite of data from NASA's Chandra X-ray Observatory and the Hubble Space Telescope is another look for NGC 6543, better known as the Cat's Eye nebula. This famous object is a so-called planetary nebula that represents a phase of stellar evolution that the Sun should experience several billion years from now. When a star like the Sun begins to run out of fuel, it becomes what is known as a red giant. In this phase, a star sheds some of its outer layers. A fast wind streaming away from the hot core rams into the ejected atmosphere, pushing it outward, and creating the graceful filamentary structures seen with optical telescopes. In the case of the Cat's Eye, material shed by the star is flying away at a speed of about 4 million miles per hour. The hot core left behind will eventually collapse to form a dense white dwarf star.

Chandra's X-ray data of the Cat's Eye, which are seen as blue in this image, show that its central star is surrounded by a cloud of multi-million-degree gas. Structures in optical light by Hubble are colored red and purple. By comparing the two, astronomers determined that the chemical composition in the region around where the hot gas is found is like that of the wind from the central star, but it is different from the cooler outer material.
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This animation shows the interaction between a "normal" star and a collapsed object such as a neutron star or a black hole. The star has reached its so-called red giant phase, where it swells to hundreds of times its original size. Those outer layers are then captured by the gravitational pull of the denser companion.
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This artist concept depicts two white dwarfs called RX J0806.3+1527 or J0806, swirling closer together, traveling in excess of a million miles per hour. As their orbit gets smaller and smaller, leading up to a merger, the system should release more and more energy in gravitational waves. This particular pair might have the smallest orbit of any known binary system. They complete an orbit in 321.5 seconds - barely more than five minutes.
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Planetary nebulas - so called because some of them resemble a planet when viewed through a small telescope - are produced in the late stages of a sun-like star's life. In this sequence, composite images of four different planetary nebulas are shown. In these images of Mz 3, BD+30-3639, Hen 3-1475, and NGC 7027, Chandra's X-ray data are seen in blue, while green and red are optical and infrared data from Hubble.
[Runtime: 0:35](X-ray: NASA/CXC/RIT/J.Kastner et al. Optical, BD +30 & Hen 3: NASA/STScI/Univ. MD/J.P.Harrington; Optical, NGC 7027: NASA/STScI/Caltech/J.Westphal & W.Latter; Optical, Mz 3: NASA/STScI/Univ. Washington/B.Balick)